USER DEVICE AND TRANSMISSION CONTROL METHOD

Description

TECHNICAL FIELD

[0001] The present invention relates to a radio communication system using carrier aggregation.

BACKGROUND ART

[0002] As a future communication standard of LTE (Long Term Evolution), 3GPP (3^rd Generation Partnership Project) is presently developing standardization of LTE-Advanced. In a LTE-Advanced system, a carrier aggregation (CA) technique is introduced to achieve a higher throughput than a LTE system while ensuring backward compatibility with the LTE system. In the carrier aggregation, a component carrier (CC) having the maximum bandwidth of 20 MHz supported by the LTE system is utilized as a basic component, and it is designed to achieve communications in a wider band by employing such multiple component carriers simultaneously.

[0003] In the carrier aggregation, a user equipment (UE) can communicate with a base station (evolved NodeB: eNB) by employing the multiple component carriers simultaneously. In the carrier aggregation, a primary cell (PCell) having high reliability for securing connectivity to a user equipment and a secondary cell (SCell) additionally configured to the user equipment being in connection to the primary cell are configured.

[0004] The primary cell is like a serving cell in the LTE system and is a cell to secure connectivity between the user equipment and a network. Specifically, in the primary cell, the user equipment can receive a PDCCH (Physical Downlink Control Channel) and a PDSCH (Physical Downlink Shared Channel) and transmit a PRACH (Physical Random Access Channel), a PUCCH (Physical Uplink Control Channel), a PUSCH (Physical Uplink Shared Channel) and a SRS (Sounding Reference Symbol). Also, if the user equipment changes the primary cell, the user equipment must perform handover. On the other hand, the secondary cell is a cell configured to the user equipment in addition to the primary cell. Addition and deletion of the secondary cell is performed by a configuration in RRC (Radio Resource Control).

[0005] See 3GPP TS 36.213 V.11.0.0 (2012-0) for the carrier aggregation, for example.

[0006] EP 2 487 945 A1 relates to a mobile communication service provided according to the configuration of a user equipment when multicarrier transmission is performed. A UE transmits a control signal to a eNB, wherein the control signal includes the "Capability" of the user equipment UE (i.e. whether or not the UE can perform carrier aggregation), information on simultaneously communicable carriers, and information on a carrier capable of transmitting an uplink signal among the simultaneously communicable carriers. The eNB performs a scheduling process in an uplink and a downlink based on the received control signal. The eNB transmits a control signal including a scheduling result to the UE. The UE to be subject to scheduling transmits an uplink signal or receives a downlink signal based on the control signal. The uplink signal may be an uplink control channel signal.

SUMMARY OF INVENTION

[PROBLEM TO BE SOLVED BY THE INVENTION]

[0007] In the current carrier aggregation, among the above-stated uplink radio channels, the PRACH, the PUCCH, the PUSCH and the SRS, transmissions of the PRACH, the PUSCH and the SRS are supported in both the primary cell and the secondary cell. In this case, the user equipment can transmit the PRACH, the PUSCH and the SRS simultaneously in the primary cell and the secondary cell.

[0008] On the other hand, in the current carrier aggregation, transmission of the PUCCH is supported in the primary cell but is not supported in the secondary cell. In other words, the PUCCH is transmitted only in the primary cell, and the transmission of the PUCCH via the secondary cell is not specified. From this reason, when a large number of user equipments use a certain cell as the primary cell, the number of user equipments allowing for connection to the primary cell will be limited due to limitation of capacity of the PUCCH in that cell. Also, according to the inter-eNB CA or the inter-site CA as presently discussed, scheduling is performed by each base station, and the PUCCH must be accordingly transmitted for each of cells configured to the user equipment. From this reason, it is being discussed that transmission of the PUCCH can be supported not only in the primary cell but also in the secondary cell.

[0009] Even if the above-stated simultaneous transmissions of the PUCCH in the multiple cells are supported in a radio communication system, however, the user equipment cannot necessarily transmit the PUCCH in the multiple cells simultaneously. For example, if the user equipment does not support a capability of the uplink simultaneous transmission, the user equipment cannot transmit the PUCCH in multiple cells simultaneously. Alternatively, if the user equipment cannot ensure an amount of transmit power sufficient to perform the uplink simultaneous transmission, for example, if the user equipment resides at a cell edge, the user equipment cannot perform the uplink simultaneous transmission.

[0010] In such a case where the user equipment cannot transmit the PUCCH in multiple cells simultaneously, it may be considered to set priority of the PUCCH for transmission and transmit the PUCCH in accordance with the priority.

[0011] In light of the above-stated problem, one objective of the present invention is to provide a technique for transmitting uplink control channels in multiple cells simultaneously in a radio communication system supporting transmission of the uplink control channels in a secondary cell.

[MEANS FOR SOLVING THE PROBLEM]

[0012] The above objective is accomplished by the subject-matter of the independent claims. The dependent claims describe advantageous embodiments.

[0013] One aspect of the present invention relates to a user equipment comprising: a transmission and reception unit configured to transmit and receive a radio channel to/from a base station via multiple cells configured by carrier aggregation; a simultaneous transmission availability determination unit configured to, in response to an occurrence of an event to transmit an uplink control channel in the multiple cells simultaneously, determine whether the uplink control channel can be simultaneously transmitted in the multiple cells; and a transmission control unit configured to, if the uplink control channel can be simultaneously transmitted in the multiple cells, instruct the transmission and reception unit to transmit the uplink control channel in the multiple cells simultaneously, and if the uplink control channel cannot be simultaneously transmitted in the multiple cells, control transmission of the uplink control channel in accordance with a transmission priority.

[ADVANTAGE OF THE INVENTION]

[0014] According to the above-mentioned aspects, it is possible to transmit uplink control channels in multiple cells simultaneously in a radio communication system supporting transmission of the uplink control channels in a secondary cell.

BRIEF DESCRIPTION OF DRAWINGS

[0015] 

FIG. 1 is a diagram for schematically illustrating a radio communication system according to one embodiment of the present invention;

FIG. 2 is a diagram for illustrating an arrangement of a user equipment according to one embodiment of the present invention; and

FIG. 3 is a flowchart for illustrating a PUCCH transmission operation according to one embodiment of the present invention.

EMBODIMENTS OF THE INVENTION

[0016] Embodiments of the present invention are described below with reference to the drawings.

[0017] Summarizing the embodiments described below, when an event to transmit uplink control channels in multiple cells simultaneously occurs in a radio communication system using carrier aggregation, a user equipment determines whether the uplink control channels for transmission can be transmitted in the multiple cells simultaneously. If the uplink control channels for transmission can be transmitted in the multiple cells simultaneously, the user equipment transmits the uplink control channels for transmission to a base station via the multiple cells. On the other hand, if the uplink control channels for transmission cannot be transmitted in the multiple cells, the user equipment controls transmissions of the uplink control channel in accordance with a transmission priority, for example, by assigning a relatively large amount of transmit power to an uplink control channel with a higher transmission priority and assigning a relatively small amount of transmit power to an uplink control channel with a lower transmission priority or stopping the transmission.

[0018] The transmission priority may depend on types of the uplink control channels for transmission. The transmission priority may be also set depending on the type of applied carrier aggregation, that is, depending on either the intra-eNB carrier aggregation or the inter-eNB carrier aggregation being applied.

[0019] In this manner, even in the case where the uplink control channels for transmission cannot be transmitted in multiple cells simultaneously, simultaneous transmission of the uplink control channels becomes possible, and accordingly a base station can receive the uplink control channel with a higher transmission priority more reliably than the uplink control channel with a lower transmission priority.

[0020] At the outset, a radio communication system according to one embodiment of the present invention is described with reference to FIG. 1. FIG. 1 is a diagram for schematically illustrating a radio communication system according to one embodiment of the present invention.

[0021] As illustrated in FIG. 1, a radio communication system 10 includes one or more base stations (eNBs) 50 and one or more user equipments (UEs) 100. In this embodiment, the radio communication system 10 is a LTE-Advanced system, but is not limited to it, and may be any appropriate radio communication system supporting the carrier aggregation.

[0022] In the radio communication system 10 according to this embodiment, the single base station 50 serves multiple cells to communicate with the user equipment 100 and communicates with the user equipment 100 via these cells by assigning a primary cell and a secondary cell from these cells to the user equipment 100 (intra-eNB CA).

[0023] Also, multiple base stations 50 serve multiple cells to communicate with the user equipment 100, and different base stations 50 assign a primary cell and a secondary cell to the user equipment 100 and communicate with the user equipment 100 via these cells (inter-eNB CA).

[0024] The base station 50 wirelessly connects to the user equipment 100 to transmit downlink data received from a communicatively connected upper station or server (not shown) to the user equipment 100 and to transmit uplink data received from the user equipment 100 to the upper station (not shown). In this embodiment, the base station 50 is an eNB in compliance with the LTE-Advanced, but is not limited to it, and may be any appropriate base station supporting the intra-eNB carrier aggregation and the inter-eNB carrier aggregation.

[0025] The user equipment 100 is typically a mobile phone, a smartphone, a tablet, a mobile router and so on, but is not limited to it, and may be any appropriate user equipment having a radio communication function. In a typical hardware arrangement, the user equipment 100 includes a CPU (Central Processing Unit) such as a processor, a memory device such as a RAM (Random Access Memory), an auxiliary storage device such as a hard disk device, a communication device for communicating wireless signals, an interface device for interfacing with a user and so on. Functions of the user equipment 100 as set forth may be implemented by loading data and programs, which are stored in the auxiliary storage device via the communication device and/or the interface device, to the memory device and then processing the data at the CPU in accordance with the loaded programs.

[0026] Next, an arrangement of the user equipment according to one embodiment of the present invention is described with reference to FIG. 2. FIG. 2 is a diagram for illustrating an arrangement of the user equipment according to one embodiment of the present invention.

[0027] As illustrated in FIG. 2, the user equipment 100 includes a transmission and reception unit 110, a simultaneous transmission availability determination unit 120 and a transmission control unit 130.

[0028] The transmission and reception unit 110 transmits and receives various radio channels such as uplink/downlink control channels and uplink/downlink data channels to/from the base station 50. In the radio communication system 10 complying with the LTE-Advanced, the user equipment 100 receives a PDCCH (Physical Downlink Control Channel) and a PDSCH (Physical Downlink Shared Channel) from the base station 50 and transmits a PRACH (Physical Random Access Channel), a PUCCH (Physical Uplink Control Channel), a PUSCH (Physical Uplink Shared Channel) and a SRS (Sounding Reference Symbol) to the base station 50.

[0029] In this embodiment, the radio communication system 10 supports carrier aggregation, and the base station 50 can communicate with the user equipment 100 via a primary cell and a secondary cell. For example, according to the intra-eNB carrier aggregation, the single base station 50 assigns a primary cell and a secondary cell to the user equipment 100 from multiple cells served by the base station 50 and communicates with the user equipment 100 via these cells. In this case, the transmission and reception unit 110 exchanges various radio channels with the base station 50 serving the cells. Also, according to the inter-eNB carrier aggregation, multiple base stations 50 assign a primary cell and a secondary cell to the user equipment 100 from respective cells and communicate with the user equipment 100 via these cells. In this case, the transmission and reception unit 110 exchanges various radio channels with the different base stations 50 serving the assigned cells. In general, according to the inter-eNB CA, the different base stations 50 use respective schedulers to assign their served cells to the user equipment 100. To this end, the respective base stations 50 would perform communication operations, such as scheduling, acknowledgement and radio quality measurement, with the user equipment 100 in parallel, and it is assumed that combinations of all uplink control information (UCI) such as a PUCCH-SR, a PUCCH-ACK/NACK and a PUCCH-CQI are transmitted simultaneously. Here, the PUCCH-SR is an uplink control channel for the user equipment 100 to issue a scheduling request to the base station 50, the PUCCH-ACK/NACK is an uplink control channel for the user equipment 100 to report whether the user equipment 100 has successfully received a data channel from the base station 50, and the PUCCH-CQI is an uplink control channel for the user equipment 100 to report radio quality such as a measured CQI (Channel Quality Indicator) to the base station 50.

[0030] The simultaneous transmission availability determination unit 120 determines, in response to an occurrence of an event to transmit an uplink control channel in multiple cells simultaneously, whether the uplink control channel can be simultaneously transmitted in the multiple cells. For example, this simultaneous transmission event may occur when the user equipment 100 transmits a scheduling request to the base station 50. Alternatively, the event may occur when the user equipment 100 receives a data channel from the base station 50 and transmits an acknowledgment indicative of whether the user equipment 100 has successfully received the data channel. Alternatively, the simultaneous transmission event may occur when the user equipment 100 is requested by the base station 50 to measure radio quality such as a CQI and report the measured radio quality or at periodic transmission timings of the radio quality.

[0031] In one embodiment, the simultaneous transmission availability determination unit 120 may determine whether the simultaneous transmission is available by determining whether the user equipment 100 has a capability of simultaneously transmitting an uplink control channel via multiple cells or whether that capability is configured. In another embodiment, the simultaneous transmission availability determination unit 120 may determine whether the simultaneous transmission is available by determining whether the user equipment 100 reserves an amount of transmit power sufficient for the simultaneous transmission. The simultaneous transmission availability determination unit 120 indicates a determination result to the transmission control unit 130.

[0032] The transmission control unit 130 controls transmission of an uplink control channel by the transmission and reception unit 110 in accordance with the received simultaneous transmission availability determination result. Specifically, if the uplink control channel can be simultaneously transmitted in the multiple cells, the transmission control unit 130 instructs the transmission and reception unit 110 to transmit the uplink control channel in the multiple cells simultaneously. On the other hand, if the uplink control channel cannot be simultaneously transmitted in the multiple cells, the transmission control unit 130 controls transmission of the uplink control channel in accordance with a configured transmission priority.

[0033] The phrase "transmission in accordance with the transmission priority" used herein may be to assign a relatively large amount of transmit power to an uplink control channel of a higher transmission priority and to assign a relatively small amount of transmit power to an uplink control channel of a lower transmission priority or stop the transmission. However, the present invention is not limited to it, and it may mean any appropriate transmission control for enabling the base station 50 to receive the uplink control channel having a higher transmission priority more reliably than the uplink control channel having a lower transmission priority.

[0034] In one embodiment, the transmission priority may be predefined in accordance with types of uplink control channels. In the radio communication system 10 complying with the LTE-Advanced, three types of PUCCHs, that is, a PUCCH-SR, a PUCCH-ACK/NACK and a PUCCH-CQI, are transmitted from the user equipment 100 to the base station 50.

[0035] For example, in a relationship between the PUCCH-SR and the PUCCH-ACK/NACK, the transmission priority may be set such that the PUCCH-SR is transmitted in priority over the PUCCH-ACK/NACK (PUCCH-SR > PUCCH-ACK/NACK). Also, the transmission priority may be set in the order of the PUCCH-SR, the PUCCH-ACK and the PUCCH-NACK (PUCCH-SR > PUCCH-ACK > PUCCH-NACK).

[0036] Also, in a relationship between the PUCCH-ACK/NACK and the PUCCH-CQI, the transmission priority may be set such that the PUCCH-ACK/NACK is transmitted in priority over the PUCCH-CQI (PUCCH-ACK/NACK > PUCCH-CQI). Also, the transmission priority may be set in the order of the PUCCH-ACK, the PUCCH-CQI and the PUCCH-NACK (PUCCH-ACK > PUCCH-CQI > PUCCH-NACK).

[0037] Also, in a relationship between the PUCCH-SR and the PUCCH-CQI, the transmission priority may be set such that the PUCCH-SR is transmitted in priority over the PUCCH-CQI (PUCCH-SR > PUCCH-CQI).

[0038] Note that the uplink control channels of the present invention are not limited to the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI as stated above and any other types of uplink control channels may be used. As can be understood from the above-stated examples, it is preferred that the transmission priority be basically specified to transmit more important uplink control channels in priority to implement radio communication between the base station 50 and the user equipment 100.

[0039] In another embodiment, the transmission priority of uplink control channels may be dynamically changed. For example, the transmission priority may be dynamically changed depending on a communication state between the base station 50 and the user equipment 100. In typical radio communication between the base station 50 and the user equipment 100, upon some communication demand arising at the user equipment 100, the user equipment 100 transmits a scheduling request to the base station 50. After scheduling, communications are initiated between the base station 50 and the user equipment 100. To this end, the transmission priority of the PUCCH-SR may be set to be higher before the communication initiation. On the other hand, after the communication initiation, the user equipment 100 receives a data channel from the base station 50 and/or transmits the data channel to the base station 50. To this end, the transmission priority of the PUCCH-ACK/NACK may be set to be higher after the communication initiation. Also, if the CQI reported from the user equipment 100 is less than or equal to a predefined threshold, there may be a higher likelihood of retransmission, and accordingly the transmission priority of the PUCCH-ACK/NACK may be set to be higher. Also, if an amount of variations of the measured CQI is larger than or equal to a predefined threshold, the transmission priority of the PUCCH-CQI may be set to be higher so that the user equipment 100 can follow variations of the radio quality quickly.

[0040] Also, the priority of the PUCCH-SR over the PUCCH-ACK/NACK and the PUCCH-CQI as stated above may be controlled, for example, based on a priority of data occurring at triggering transmission of the PUCCH-SR. For example, if the occurring data has a lower priority or a less rigorous latency requirement, the PUCCH-ACK/NACK and the PUCCH-CQI may have a priority over the PUCCH-SR.

[0041] In another embodiment, the transmission priority of uplink control channels may be indicated from the base station 50. In the radio communication system 10 complying with the LTE-Advanced, for example, the base station 50 may set the transmission priority of the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI for transmission and indicate the transmission priority to the user equipment 100. Also, the base station 50 may dynamically set the priority depending on communication state to the user equipment 100 and indicate the priority to the user equipment 100. For example, in the case where a large number of user equipments 100 are connecting to the base station 50, it may not be preferable that the base station 50 intensively receives one certain type of uplink control channel (such as the PUCCH-SR). In fact, upon receiving the PUCCH-SRs from the large number of user equipments 100 simultaneously, the base station 50 would temporarily have heavy processing load associated with scheduling. In order to avoid such a situation, for example, the base station 50 may divide the connecting user equipments 100 into multiple groups and set different transmission priorities for the different groups dynamically.

[0042] In another embodiment, the transmission priority may be set depending on component carriers or cells. For example, transmission of an uplink control channel in a primary cell may be prioritized over transmission of an uplink control channel in a secondary cell. For example, if the PUCCH-CQI is transmitted in multiple cells, the transmission priority may be set so that the PUCCH-CQI in the primary cell can be transmitted in priority over the PUCCH-CQI in the secondary cell (PCell CQI > SCell CQI).

[0043] Also, if two or more secondary cells are configured, the transmission priority among the secondary cells may be set in accordance with the order of communication quality in the secondary cells, indices of the secondary cells (SCellIndex) and so on. Here, SCellIndex is assigned whenever a secondary cell is assigned to the user equipment 100. For example, SCellIndex is set to 1 for the first-assigned secondary cell (SCellIndex = 1), SCellIndex is set to 2 for the second-assigned secondary cell (SCellIndex = 2), and so on.

[0044] Also, the transmission priority may be set in accordance with a communication scheme in a component carrier or a cell configured to the user equipment 100. For example, in accordance with which of TDD (Time Division Duplex) scheme or FDD (Frequency Division Duplex) scheme is used in the cell, a relatively higher transmission priority may be set for the TDD scheme cell, and a relatively lower transmission priority may be set for the FDD scheme cell.

[0045] In one embodiment, the transmission control unit 130 may have a CA type determination unit 131 configured to determine whether the user equipment 100 uses the intra-eNB carrier aggregation or the inter-eNB carrier aggregation. In this case, the transmission control unit 130 determines the transmission priority of the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI depending on whether the user equipment 100 uses the intra-eNB carrier aggregation or the inter-eNB carrier aggregation. For example, this CA type determination may be made by identifying the base station(s) 50 serving component carriers or cells assigned to the user equipment 100.

[0046] Depending on a CA type used by the user equipment 100, the transmission control unit 130 controls the transmission priority of various uplink control channels of the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI. If the user equipment 100 uses the intra-eNB CA, the transmission control unit 130 controls transmissions of the various uplink control channels in accordance with the above-stated transmission priority. In other words, the transmission control unit 130 determines the transmission priority of the uplink control channels in accordance with one or more of a transmission priority based on types of uplink control channels, a transmission priority indicated from the base station 50 and a transmission priority of multiple cells, and controls to transmit the uplink control channels to the base station 50 via the corresponding cells in accordance with the determined transmission priority.

[0047] On the other hand, if the user equipment 100 uses the inter-eNB CA, the transmission control unit 130 may further use various transmission priorities as set forth. In general, different base stations 50 and schedulers are used in the inter-eNB CA. From this reason, the respective base stations 50 will perform communication operations, such as scheduling, acknowledgement and radio quality measurement, with the user equipment 100 in parallel, and it is assumed that a combination of all uplink control information (UCI) such as the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI will be transmitted simultaneously.

[0048] In one embodiment, the base station 50 serving any cell connected by the user equipment 100 is configured as an anchor base station (eNB), and transmission of an uplink control channel to the anchor base station 50 may be prioritized. In other words, an uplink control channel transmitted to a component carrier or a cell served by the anchor base station 50 may be transmitted in priority over an uplink control channel transmitted to a component carrier or a cell served by a non-anchor base station 50'. For example, the uplink control channel transmitted to a component carrier or a cell served by the anchor base station 50 may be transmitted at a higher transmission power than the uplink control channel transmitted to a component carrier or a cell served by the non-anchor base station 50', or transmission of the uplink control channel to the component carrier or the cell served by the non-anchor base station 50' may be stopped.

[0049] The anchor base station 50 may be selected in accordance with any criteria. In one embodiment, the anchor base station 50 may be a base station having a primary cell configured. In another embodiment, the anchor base station 50 may be a base station serving a certain protocol layer collectively. In the LTE-Advanced system, for example, protocol layers of RRC (Radio Resource Control), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control) and PHY are used, and the base station collectively serving certain one of these protocol layers may be configured as the anchor base station 50.

[0050] In another embodiment, the anchor base station 50 may be a base station having a SRB (Signaling Radio Bearer) configured. Alternatively, the anchor base station 50 may be a base station managing an interface to a core node. Alternatively, the anchor base station 50 may be a base station having security configured. In this case, the anchor base station 50 collectively performs security operations for communications between the user equipment 100 and the anchor base station 50 and other non-anchor base stations 50'.

[0051] In another embodiment, the anchor base station 50 may be a macro base station. In other words, in the LTE-Advanced system, a heterogeneous network (HetNet) where multiple types of base stations covering different cell radius are used is discussed. For example, a macro base station is used as a high power output type of base station covering a relatively large cell radius, and a pico base station is used as a low power output type of base station covering a relatively small cell radius. Alternatively, a femto base station for indoor use is used. The anchor base station 50 may be any of these different types of base stations.

[0052] In another embodiment, the anchor base station 50 may be a stand-alone type of base station that can provide a communication service to the user equipment 100 singularly.

[0053] In another embodiment, for example, if the inter-eNB CA is performed among three or more base stations 50, the priority may be set in the descending or ascending order of identifiers (indices) of the base stations 50.

[0054] In another embodiment, the transmission priority may be set in the goodness or badness order of radio quality between the user equipment 100 and the respective base stations 50. For example, the transmission priority may be set in the goodness or badness order of downlink or uplink radio quality.

[0055] In another embodiment, the priority may be set for each base station 50 in the radio communication system 10, and transmission of an uplink control channel to the respective base stations 50 may be controlled in accordance with the priorities.

[0056] In another embodiment, transmission of an uplink control channel to respective base stations 50 may be controlled in accordance with a priority of a bearer associated with communication in each component carrier or cell. For example, the priority of SRB data may be set to be the highest, the priority of high QoS (Quality of Service) data such as sound may be set to be the second highest, and finally the priority of low QoS data such as BE data may be set to be the lowest.

[0057] In another embodiment, transmission of an uplink control channel to respective base stations 50 may be controlled in accordance with average data rates available in the respective base stations 50. The average data rate can be measured by the user equipment 100.

[0058] In another embodiment, the transmission priority may be preset in accordance with types of uplink control channels. In the inter-eNB CA where different schedulers are used for scheduling, it is assumed that the PUCCH-SR may be simultaneously transmitted in multiple cells unlike the intra-eNB CA where a single scheduler is used for scheduling. If the PUCCH-SR cannot be simultaneously transmitted in the multiple cells in this situation, and accordingly the priority control is applied, some transmission priority must be set. For example, the PUCCH-SR having a lesser number of transmission times, that is, the PUCCH-SR having a lesser number of retransmission times, may be transmitted in priority. This is because it can be considered that a newer scheduling request may reflect a later communication demand of the user equipment 100.

[0059] Also, as stated above, different base stations 50 or schedulers are used in the inter-eNB CA. From this reason, the respective base stations 50 would perform communication operations, such as scheduling, acknowledgement and radio quality measurement, with the user equipment 100 in parallel, and it is assumed that a combination of all uplink control information (UCI) such as the PUCCH-SR, the PUCCH-ACK/NACK and the PUCCH-CQI may be simultaneously transmitted. In the inter-eNB CA where different schedulers are used for scheduling as stated above, it is assumed that the PUCCH-ACK/NACK may be simultaneously transmitted in multiple cells. If the PUCCH-ACK/NACK cannot be simultaneously transmitted in this situation and accordingly the priority control is applied, some transmission priority must be set. For example, the PUCCH-ACK may be transmitted in priority over the PUCCH-NACK. This is because it can be considered that if the base station 50 cannot receive the PUCCH-ACK within a predefined period even without receipt of the PUCCH-NACK, the base station 50 determines that reception has not been successful at the user equipment 100 and performs retransmission. Alternatively, if the PUCCH-NACK is transmitted, the priority may be controlled in consideration of how many times HARQ (Hybrid Automatic Repeat Request) has been performed until current transmission of the PUCCH-NACK. In one embodiment, the PUCCH-NACK for earlier HARQ may be transmitted in priority. In this case, for example, if the PUCCH-NACK for the third HARQ and the PUCCH-NACK for the fifth HARQ are considered, the PUCCH-NACK for the third HARQ may be transmitted in priority.

[0060] The above-stated various settings of transmission priority may be used singularly or in combination. For example, if the above embodiment where transmission to the anchor base station is prioritized is combined with the embodiment where SCellIndex is used, the transmission of an uplink control channel to the anchor base station is first prioritized, and then the transmission priority among non-anchor base stations may be set by using SCellIndex.

[0061] Next, a simultaneous transmission operation of an uplink control channel in the user equipment according to one embodiment of the present invention is described with reference to FIG. 3. FIG. 3 is a flow diagram for illustrating a PUCCH transmission operation according to one embodiment of the present invention.

[0062] As illustrated in FIG. 3, at step S101, the user equipment 100 detects any event for transmitting a PUCCH in multiple cells simultaneously. For example, the event may occur when the user equipment 100 has issued a scheduling request to the base station 50, when the user equipment 100 receives a data channel from the base station 50 and transmits an acknowledgement indicative of whether the data channel has been successfully received, or when the user equipment 100 has been requested by the base station 50 to measure radio quality such as a CQI and report the measured radio quality.

[0063] At step S102, in response to the event, the simultaneous transmission availability determination unit 120 determines whether the PUCCH can be simultaneously transmitted in multiple cells. In one embodiment, the simultaneous transmission availability determination unit 120 may determine whether the simultaneous transmission is available by determining whether a capability of simultaneously transmitting the PUCCH via the multiple cells has been configured to the user equipment 100. In another embodiment, the simultaneous transmission availability determination unit 120 may determine whether the simultaneous transmission is available by determining whether the user equipment 100 can reserve an amount of transmission power sufficient for simultaneous transmission.

[0064] If it is determined that the PUCCH can be simultaneously transmitted in the multiple cells (S102:Y), the flow proceeds to step S103, and the transmission control unit 130 instructs the transmission and reception unit 110 to simultaneously transmit the PUCCH in the multiple cells.

[0065] On the other hand, if it is not determined that the PUCCH can be simultaneously transmitted in the multiple cells (S102:N), the flow proceeds to step S104, and the transmission control unit 130 prioritizes the PUCCH for transmission in accordance with a transmission priority and instructs the transmission and reception unit 110 to transmit the PUCCH to the base station 50 in accordance with the priority.

[0066] In one embodiment, the transmission control unit 130 may determine which of the intra-eNB CA or the inter-eNB CA is applied and prioritize the PUCCH for transmission depending on the intra-eNB CA or the inter-eNB CA.

[0067] If the intra-eNB CA is applied, the transmission control unit 130 may determine the transmission priority of the PUCCH for transmission in accordance with one or more of a predefined or dynamically configured priority based on the type of PUCCH, a priority indicated from the base station 50 and a priority of cells, and transmit the PUCCH for transmission to the single base station 50 via the corresponding cell in accordance with the determined transmission priority.

[0068] On the other hand, if the inter-eNB CA is applied, the transmission control unit 130 determines the transmission priority of the PUCCH for transmission in accordance with one or more priorities of a priority for prioritizing the anchor base station 50, a priority based on the order of identifiers of respective base stations 50, a priority based on goodness of radio quality between the user equipment 100 and the respective base stations 50, priorities configured for the respective base stations 50, a priority of a bearer associated with the respective base stations 50 and average data rates available in the respective base stations, in addition to/instead of one or more of the predefined or dynamically configured priority based on the type of PUCCH, the priority indicated from the base station 50 and the priority of cells for use in the intra-eNB CA case, and transmit the PUCCH for transmission to connecting different base stations 50 via the corresponding cells in accordance with the determined transmission priority.

[0069] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-stated specific embodiments.

LIST OF REFERENCE SYMBOLS

[0070] 

10: radio communication system

50: base station 50' non-anchor base station

100: user equipment

110: transmission and reception unit

120: simultaneous transmission availability determination unit

130: transmission control unit

131: carrier aggregation type determination unit

Claims

1. A user equipment (100) comprising:

a transmission and reception unit (110) configured to transmit and receive a radio channel to/from a base station (50) via multiple cells configured by carrier aggregation;

a simultaneous transmission availability determination unit (120) configured to, in response to an occurrence in the user equipment of an event to transmit an uplink control channel in the multiple cells simultaneously, determine whether the uplink control channel can be simultaneously transmitted by the user equipment in the multiple cells; and

a transmission control unit (130) configured to, if the uplink control channel can be simultaneously transmitted by the user equipment in the multiple cells, instruct the transmission and reception unit (110) to transmit the uplink control channel in the multiple cells simultaneously, and if the uplink control channel cannot be simultaneously transmitted by the user equipment in the multiple cells, control transmission of the uplink control channel in accordance with a transmission priority, wherein

the transmission control unit (130) includes a carrier aggregation type determination unit (131) configured to determine which of intra-eNB carrier aggregation or inter-eNB carrier aggregation is applied, and the transmission control unit (130) sets the transmission priority depending on the determination, and

the transmission control unit (130) is configured to assign a relatively large amount of transmit power to an uplink control channel having the high transmission priority and assigns a relatively small amount of transmit power to an uplink control channel having the low transmission priority or stops the transmission.

2. The user equipment as claimed in claim 1, wherein if the inter-eNB carrier aggregation is applied, the transmission control unit (130) determines the transmission priority of an uplink control channel in accordance with one or more of a priority based on a type of the uplink control channel, a priority indicated from the base station, a priority of the multiple cells, a priority for prioritizing an anchor base station, a priority based on an order of identifiers of respective base stations, a priority based on goodness of radio quality between respective base stations and the user equipment, priorities configured for respective base stations, a priority of a bearer associated with respective base stations and average data rates available in respective base stations and controls to transmit the uplink control channel to the base station via a corresponding cell in accordance with the determined transmission priority.

3. The user equipment (100) as claimed in claim 1 or 2, wherein if the intra-eNB carrier aggregation is applied, the transmission control unit (130) determines the transmission priority of an uplink control channel in accordance with one or more of a priority based on a type of the uplink control channel, a priority indicated from the base station and a priority of the multiple cells and controls to transmit the uplink control channel to the base station via a corresponding cell in accordance with the determined transmission priority.

4. The user equipment (100) as claimed in claim 2 or 3, wherein the type of the uplink control channel includes an uplink control channel for transmitting a scheduling request, an acknowledgement and a radio quality report, and the transmission priority follows an order of an uplink control channel for transmitting the scheduling request, an uplink control channel for transmitting the acknowledgement and an uplink control channel for transmitting the radio quality report.

5. The user equipment (100) as claimed in claim 2 or 3, wherein the priority of the multiple cells is set such that the highest priority is assigned to a primary cell, and the priority among secondary cells follows an order of goodness of radio quality or indices assigned to the secondary cells.

6. The user equipment (100) as claimed in claim 1, wherein if the inter-eNB carrier aggregation is applied, the transmission control unit (130) prioritizes transmission of a scheduling request of a lesser number of transmission times among multiple scheduling requests simultaneously transmitted in the multiple cells.

7. The user equipment (100) as claimed in claim 1, wherein if the inter-eNB carrier aggregation is applied, the transmission control unit (130) prioritizes transmission of an ACK among multiple ACKs and NACKs simultaneously transmitted in the multiple cells.

8. A transmission control method in a user equipment for transmitting and receiving a radio channel to/from a base station via multiple cells configured by carrier aggregation, comprising:

detecting (S101) an occurrence in the user equipment of an event to transmit an uplink control channel in the multiple cells simultaneously;

determining (S102) whether the uplink control channel can be simultaneously transmitted by the user equipment in the multiple cells; and

if the uplink control channel can be simultaneously transmitted by the user equipment in the multiple cells, transmitting (S103) the uplink control channel in the multiple cells simultaneously, and if the uplink control channel cannot be simultaneously transmitted by the user equipment in the multiple cells, controlling (S104) transmission of the uplink control channel in accordance with a transmission priority such that the base station receives an uplink control channel having a higher transmission priority more reliably than an uplink control channel having a lower transmission priority, and

determining which of intra-eNB carrier aggregation or inter-eNB carrier aggregation is applied, and setting the transmission priority depending on the determination, wherein

a relatively large amount of transmit power is assigned to an uplink control channel having the high transmission priority and a relatively small amount of transmit power is assigned to an uplink control channel having the low transmission priority or stops the transmission.

Ansprüche

1. Anwenderendgerät (100), umfassend:

eine Sende- und Empfangseinheit (110) konfiguriert, um einen Funkkanal zu/von einer Basisstation zu senden und zu empfangen (50), über Mehrfachzellen, die mittels Trägeraggregation konfiguriert sind;

eine simultane Bestimmungseinheit der Übertragungsverfügbarkeit (120) konfiguriert, um, in Antwort auf das Auftreten eines zu sendenden Ereignisses im Anwenderendgerät, simultan einen Uplink-Steuerkanal in die Mehrfachzellen zu übertragen, festzustellen, ob der Uplink-Steuerkanal simultan vom Anwenderendgerät in die Mehrfachzellen übertragen werden kann; und

eine Übertragungssteuereinheit (130) konfiguriert, um, wenn der Uplink-Steuerkanal simultan vom Anwenderendgerät in die Mehrfachzellen übertragen werden kann, die Übertragungs- und Empfangseinheit (110) anzuweisen, den Uplink-Steuerkanal simultan in die Mehrfachzellen zu übertragen, und wenn der Uplink-Steuerkanal nicht simultan vom Anwenderendgerät in den Mehrfachzellen übertragen werden, die Übertagung des Uplink-Steuerkanal gemäß einer Übertragungspriorität zu steuern, wobei

die Übertragungssteuereinheit (130) eine Bestimmungseinheit der Trägeraggregation des Typs (131) aufweist, die konfiguriert ist, um festzustellen, welche Intra-eNB-Trägeraggregation oder Inter-eNB-Trägeraggregation angewandt wird und die Übertragungssteuereinheit (130) legt die Übertragungspriorität abhängig von der Bestimmung fest, und

die Übertragungssteuereinheit (130) konfiguriert ist, eine relativ große Menge Übertragungsleistung einem Uplink-Steuerkanal zuzuweisen, der die hohe Übertragungspriorität hat und eine relativ kleine Menge Übertragungsleistung dem Uplink-Steuerkanal zuzuweisen, der die geringe Übertragungspriorität hat oder die Übertragung stoppt.

2. Anwenderendgerät nach Anspruch 1, wobei bei Anwendung der Inter-eNB-Trägeraggregation die Übertragungssteuereinheit (130) die Übertragungspriorität eines Uplink-Steuerkanals im Einklang mit einer oder mehreren prioritätsbasierten Arten des Uplink-Steuerkanals festlegt, eine von der Basisstation indizierte Priorität, eine Priorität der Mehrfachzellen, eine Priorität zum Priorisieren einer Anker-Basisstation, eine Priorität basierend auf einer Reihenfolge von Kennungen von jeweiligen Basisstationen, eine Priorität basierend auf der Güte der Funkqualität zwischen den jeweiligen Basisstationen und dem Anwenderendgerät, Prioritäten konfiguriert für jeweilige Basisstationen, eine Priorität eines Trägers, der mit den jeweiligen Basisstationen verbunden ist und durchschnittliche Datenraten, die in den entsprechenden Basisstationen verfügbar sind und Steuerelemente, um den Uplink-Steuerkanal über eine entsprechende Zelle an die Basisstation zu übertagen, im Einklang mit der festgelegten Übertragungspriorität.

3. Anwenderendgerät (100) nach Anspruch 1 oder 2, wobei bei Anwendung der Intra-eNB-Trägeraggregation die Übertragungssteuereinheit (130) die Übertragungspriorität eines Uplink-Steuerkanals im Einklang mit einer oder mehreren prioritätsbasieren Arten des Uplink-Steuerkanals festlegt, eine von der Basisstation indizierte Priorität und eine Priorität der Mehrfachzellen und Steuerelemente zur Übertragung des Uplink-Steuerkanals an die Basisstation über eine entsprechende Zelle im Einklang mit der festgelegten Übertragungspriorität.

4. Anwenderendgerät (100) nach Anspruch 2 oder 3, wobei die Art des Uplink-Steuerkanals einen Uplink-Steuerkanal für die Übertragung einer Planungsanfrage, einer Bestätigung und eines Funkqualitätsberichts aufweist und die Übertragungspriorität einer Reihenfolge eines Uplink-Steuerkanals für die Übertragung der Planungsanfrage, eines Uplink-Steuerkanals für die Übertragung der Bestätigung und eines Uplink-Steuerkanals für die Übertragung des Funkqualitätsberichts folgt.

5. Anwenderendgerät (100) nach Anspruch 2 oder 3, wobei die Priorität der Mehrfachzellen so eingestellt ist, dass die höchste Priorität einer Primärzelle zugewiesen wird und die Priorität der sekundären Zellen eine Reihenfolge der Güte der Funkqualität befolgt oder Indizes, die den sekundären Zellen zugewiesen sind.

6. Anwenderendgerät (100) nach Anspruch 1, wobei bei Anwendung der Inter-eNB-Trägeraggregation die Übertragungssteuereinheit (130) Übertragungen einer Planungsanfrage einer geringeren Anzahl von Übertragungszeiten unter den mehreren simultan an die Mehrfachzellen übertragenen Planungsanfragen priorisiert.

7. Anwenderendgerät (100) nach Anspruch 1, wobei bei Anwendung der Inter-eNB-Trägeraggregation die Übertragungssteuereinheit (130) die Übertragung eines ACK zwischen mehrfachen ACKs und NACKs priorisiert, die gleichzeitig in die Mehrfachzellen übertragen werden.

8. Übertragungssteuerverfahren in einem Anwenderendgerät zum Übertragen und Empfangen eines Funkkanals zu/von einer Basisstation mittels Mehrfachzellen, die durch Trägeraggregation konfiguriert sind, umfassend:

Erfassen (S101) eines Ereignisses zur simultanen Übertagung eines Uplink-Steuerkanals in die Mehrfachzellen im Anwenderendgerät;

Feststellen (S102), ob der Uplink-Steuerkanal simultan vom Anwenderendgerät in die Mehrfachzellen übertragen werden kann; und

wenn der Uplink-Steuerkanal vom Anwenderendgerät simultan in die Mehrfachzellen übertragen werden kann, simultanes
Übertragen (S103) des Uplink-Steuerkanals in the Mehrfachzellen und, wenn der Uplink-Steuerkanal nicht simultan vom Anwenderendgerät in the Mehrfachzellen übertragen werden kann, Steuern (S104) der Übertragung des Uplink-Steuerkanals im Einklang mit einer Übertragungspriorität, sodass die Basisstation einen Uplink-Steuerkanal empfängt, der eine höhere Übertragungspriorität mit größerer Zuverlässigkeit hat als ein Uplink-Steuerkanal mit einer geringeren Übertragungspriorität, und

Feststellen, ob Intra-eNB-Trägeraggregation oder Inter-eNB-Trägeraggregation angewendet wird und Einstellen der Übertragungspriorität gemäß der Festlegung, wobei

eine relativ große Menge Übertragungsleistung einem Uplink-Steuerkanal zugewiesen wird, der die hohe Übertragungspriorität hat und eine relativ kleine Menge Übertragungsleistung dem Uplink-Steuerkanal zugewiesen wird, der die geringe Übertragungspriorität hat oder die Übertragung stoppt.

Revendications

1. Équipement utilisateur (100) comprenant :

une unité d'émission et de réception (110) configurée pour émettre et recevoir un canal radio vers/en provenance d'une station de base (50) via des cellules multiples configurées par agrégation de porteuses ;

une unité de détermination de disponibilité d'émission simultanée (120) configurée pour, en réponse à une survenance dans l'équipement utilisateur d'un événement pour émettre un canal de commande de liaison montante dans les cellules multiples simultanément, déterminer si le canal de commande de liaison montante peut être émis simultanément par l'équipement utilisateur dans les cellules multiples ; et

une unité de commande d'émission (130) configurée pour, si le canal de commande de liaison montante peut être émis simultanément par l'équipement utilisateur dans les cellules multiples, charger l'unité d'émission et de réception (110) d'émettre le canal de commande de liaison montante dans les cellules multiples simultanément, et si le canal de commande de liaison montante ne peut pas être émis simultanément par l'équipement utilisateur dans les cellules multiples, commander l'émission du canal de commande de liaison montante selon une priorité d'émission, dans lequel

l'unité de commande d'émission (130) inclut une unité de détermination de type d'agrégation de porteuses (131) configurée pour déterminer laquelle d'une agrégation de porteuses intra-eNB ou d'une agrégation de porteuses inter-eNB est appliquée, et l'unité de commande d'émission (130) fixe la priorité d'émission en fonction de la détermination, et

l'unité de commande d'émission (130) est configurée pour attribuer une quantité relativement grande de puissance d'émission à un canal de commande de liaison montante ayant la priorité d'émission élevée, et attribue une quantité relativement petite de puissance d'émission à un canal de commande de liaison montante ayant la priorité d'émission basse, ou arrête l'émission.

2. Équipement utilisateur selon la revendication 1, dans lequel si l'agrégation de porteuses inter-eNB est appliquée, l'unité de commande d'émission (130) détermine la priorité d'émission d'un canal de commande de liaison montante selon une ou plusieurs d'une priorité basée sur un type du canal de commande de liaison montante, d'une priorité indiquée par la station de base, d'une priorité des cellules multiples, d'une priorité pour donner la priorité à une station de base d'ancrage, d'une priorité basée sur un ordre d'identificateurs de stations de base respectives, d'une priorité basée sur une validité de qualité radio entre des stations de base respectives et l'équipement utilisateur, de priorités configurées pour des stations de base respectives, d'une priorité d'un porteur associé à des stations de base respectives et des débits de données moyens disponibles dans des stations de base respectives et des commandes pour émettre le canal de commande de liaison montante à la station de base via une cellule correspondante selon la priorité d'émission déterminée.

3. Équipement utilisateur (100) selon la revendication 1 ou 2, dans lequel si l'agrégation de porteuses intra-eNB est appliquée, l'unité de commande d'émission (130) détermine la priorité d'émission d'un canal de commande de liaison montante selon une ou plusieurs d'une priorité basée sur un type du canal de commande de liaison montante, d'une priorité indiquée par la station de base et d'une priorité des cellules multiples, et commande pour émettre le canal de commande de liaison montante vers la station de base via une cellule correspondante selon la priorité d'émission déterminée.

4. Équipement utilisateur (100) selon la revendication 2 ou 3, dans lequel le type du canal de commande de liaison montante inclut un canal de commande de liaison montante pour émettre une demande de planification, un accusé de réception et un rapport de qualité radio, et la priorité d'émission suit un ordre d'un canal de commande de liaison montante pour émettre la demande de planification, d'un canal de commande de liaison montante pour émettre l'accusé de réception et d'un canal de commande de liaison montante pour émettre le rapport de qualité radio.

5. Équipement utilisateur (100) selon la revendication 2 ou 3, dans lequel la priorité des cellules multiples est fixée de sorte que la priorité la plus haute est attribuée à une cellule primaire, et la priorité parmi des cellules secondaires suit un ordre de validité de qualité radio ou des indices attribués aux cellules secondaires.

6. Équipement utilisateur (100) selon la revendication 1, dans lequel si l'agrégation de porteuses inter-eNB est appliquée, l'unité de commande d'émission (130) donne la priorité à l'émission d'une demande de planification d'un nombre moindre d'instants d'émission parmi des demandes de planification multiples émises simultanément dans les cellules multiples.

7. Équipement utilisateur (100) selon la revendication 1, dans lequel si l'agrégation de porteuses inter-eNB est appliquée, l'unité de commande d'émission (130) donne la priorité à l'émission d'un ACK parmi de multiples ACK et NACK émis simultanément dans les cellules multiples.

8. Procédé de commande d'émission dans un équipement utilisateur pour émettre et recevoir un canal radio vers/en provenance d'une station de base via des cellules multiples configurées par agrégation de porteuses, comprenant :

la détection (S101) d'une survenance dans l'équipement utilisateur d'un événement pour émettre un canal de commande de liaison montante dans les cellules multiples simultanément;

la détermination (S102) que le canal de commande de liaison montante peut être ou non émis simultanément par l'équipement utilisateur dans les cellules multiples ; et

si le canal de commande de liaison montante peut être émis simultanément par l'équipement utilisateur dans les cellules multiples, l'émission (S103) du canal de commande de liaison montante dans les cellules multiples simultanément, et si le canal de commande de liaison montante ne peut pas être émis simultanément par l'équipement utilisateur dans les cellules multiples, la commande (S104) de l'émission du canal de commande de liaison montante selon une priorité d'émission de sorte que la station de base reçoit un canal de commande de liaison montante ayant une priorité d'émission plus haute de façon plus fiable qu'un canal de commande de liaison montante ayant une priorité d'émission inférieure, et

la détermination de celle d'une agrégation de porteuses intra-eNB ou d'une agrégation de porteuses inter-eNB qui est appliquée, et la fixation de la priorité d'émission selon la détermination, dans lequel

une quantité relativement grande de puissance d'émission est attribuée à un canal de commande de liaison montante ayant la priorité d'émission haute et une quantité relativement petite de puissance d'émission est attribuée à un canal de commande de liaison montante ayant la priorité d'émission basse, ou l'émission s'arrête.

Drawing